Put the oatmeal, flour, seeds, salt and pepper in a bowl or food processor. Add the butter and rub in with the fingertips or process until the mixture resembles breadcrumbs. Add the measurement water and mix or blend to a firm dough, adding a little more water if the dough feels dry.
Roll out the dough on a lightly floured surface to 2.5 mm (⅛ inch) thick. Cut out 20 rounds using a 6 cm (2½ inch) plain or fluted biscuit cutter, re-rolling the trimmings to make more. Place slightly apart on a large greased baking sheet.
Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for about 25 minutes until firm. Transfer to a wire rack to cool. Serve with cheese.